forked from osmocom/wireshark
367954ea2d
Let the tvbuff mechanism check the length of the packet - don't check it ourselves. Put each field into the protocol tree and the Info column separately, so that we at least get a partial dissection - I've seen some packets that look like breath-of-life packets but that have only the PDU field. Show the PDU field with all 8 hex digits, and show the sequence number as an unsigned quantity, in the Info column. Show the padding size based on the actual length of the frame, not on the amount of the frame that was captured. svn path=/trunk/; revision=7238
141 lines
3.9 KiB
C
141 lines
3.9 KiB
C
/* packet-bofl.c
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* Routines for Wellfleet BOFL dissection
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* Author: Endoh Akira (endoh@netmarks.co.jp)
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*
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* $Id: packet-bofl.c,v 1.3 2003/03/01 09:37:38 guy Exp $
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*
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* Ethereal - Network traffic analyzer
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* By Gerald Combs <gerald@unicom.net>
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* Copyright 1998 Gerald Combs
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*
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* The following information was copied from
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* http://www.protocols.com/pbook/bridge.htm#WellfleetBOFL
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*
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* The Wellfleet Breath of Life (BOFL) protocol is used as a line sensing
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* protocol on:
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*
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* - Ethernet LANs to detect transmitter jams.
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* - Synchronous lines running WFLT STD protocols to determine if the line
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* is up.
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* - Dial backup PPP lines.
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*
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* The frame format of Wellfleet BOFL is shown following the Ethernet header
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* in the following illustration:
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*
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* Destination Source 8102 PDU Sequence Padding
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* 6 6 2 4 4 n bytes
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*/
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#ifdef HAVE_CONFIG_H
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# include "config.h"
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#endif
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#include <glib.h>
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#include <epan/packet.h>
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#define ETHER_TYPE_BOFL 0x8102
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#define BOFL_MIN_LEN 8
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/* Initialize the protocol and registered fields */
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static int proto_bofl = -1;
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static int hf_bofl_pdu = -1;
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static int hf_bofl_sequence = -1;
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/* Initialize the subtree pointers */
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static gint ett_bofl = -1;
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/* Code to actually dissect the packets */
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static void
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dissect_bofl(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
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{
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proto_item *ti;
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proto_tree *bofl_tree = NULL;
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gint len;
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guint32 pdu, sequence;
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if (check_col(pinfo->cinfo, COL_PROTOCOL))
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col_set_str(pinfo->cinfo, COL_PROTOCOL, "BOFL");
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if (check_col(pinfo->cinfo, COL_INFO))
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col_clear(pinfo->cinfo, COL_INFO);
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if (tree) {
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ti = proto_tree_add_item(tree, proto_bofl, tvb, 0, -1, FALSE);
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bofl_tree = proto_item_add_subtree(ti, ett_bofl);
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}
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pdu = tvb_get_ntohl(tvb, 0);
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if (check_col(pinfo->cinfo, COL_INFO)) {
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col_add_fstr(pinfo->cinfo, COL_INFO,
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"PDU: 0x%08x", pdu);
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}
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if (tree)
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proto_tree_add_uint(bofl_tree, hf_bofl_pdu, tvb, 0, 4, pdu);
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sequence = tvb_get_ntohl(tvb, 4);
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if (check_col(pinfo->cinfo, COL_INFO)) {
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col_append_fstr(pinfo->cinfo, COL_INFO,
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" Sequence: %u", sequence);
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}
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if (tree) {
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proto_tree_add_uint(bofl_tree, hf_bofl_sequence, tvb, 4, 4, sequence);
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len = tvb_length_remaining(tvb, 8);
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if (len > 0)
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proto_tree_add_text(bofl_tree, tvb, 8, len,
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"Padding (%d byte)", len);
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}
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}
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void
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proto_register_bofl(void)
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{
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static hf_register_info hf[] = {
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{ &hf_bofl_pdu,
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{ "PDU", "bofl.pdu",
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FT_UINT32, BASE_HEX, NULL, 0,
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"PDU; normally equals 0x01010000 or 0x01011111", HFILL }
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},
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{ &hf_bofl_sequence,
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{ "Sequence", "bofl.sequence",
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FT_UINT32, BASE_DEC, NULL, 0,
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"incremental counter", HFILL }
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}
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};
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static gint *ett[] = {
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&ett_bofl,
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};
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proto_bofl = proto_register_protocol("Wellfleet Breath of Life",
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"BOFL", "bofl");
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proto_register_field_array(proto_bofl, hf, array_length(hf));
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proto_register_subtree_array(ett, array_length(ett));
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}
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void
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proto_reg_handoff_bofl(void)
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{
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dissector_handle_t bofl_handle;
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bofl_handle = create_dissector_handle(dissect_bofl, proto_bofl);
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dissector_add("ethertype", ETHER_TYPE_BOFL, bofl_handle);
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}
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